


teacher's aid

by WattStalf



Series: Commissions [158]
Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Fingering, Anal Sex, Blow Jobs, Cunnilingus, Double Penetration, F/M, Multi, Nipple Play, Teacher-Student Relationship, Threesome - F/M/M, Vaginal Sex, commission
Language: English
Status: Completed
Published: 2020-08-14
Updated: 2020-08-14
Packaged: 2021-03-06 00:37:01
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 4,025
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25904455
Author URL: https://archiveofourown.org/users/WattStalf/pseuds/WattStalf
Summary: Sylvain and Dimitri have noticed how hard Byleth works, so the two of them want to do something to help her relax.
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth, Dimitri Alexandre Blaiddyd/Sylvain Jose Gautier/My Unit | Byleth, Sylvain Jose Gautier/My Unit | Byleth
Series: Commissions [158]
Series URL: https://archiveofourown.org/series/1325462
Comments: 1
Kudos: 72





	teacher's aid

Byleth is such a hard worker that she often wears herself out performing her duties as the professor of the Blue Lion house. Her students notice this, with two students in particular taking notice of just how tired she really is, both knowing just how much she does for her class. Both want to be able to help her out, with one already having an idea that he is hoping to execute, while another, though completely clueless about how to do it, is no less determined to help Byleth relax and pay her back for her hard work.

Dimitri feels as though it is his duty, as head of his class, and with Sylvain knowing just how concerned Dimitri is, it is easy to get him to talk to him about it, so that his more… _mature_ classmate can help put the right ideas in his head. After all, he knows for a fact that having two of them involved instead of just him will only make this better for Byleth, and she deserves the best that her students can possibly give her.

Perhaps his eagerness to show her a good time partially stems from guilt over how rude he was to her when they first met. Whatever the case, he is not going to let this opportunity pass him by, so when he gets Dimitri to admit that he is looking for something to do for Byleth, Sylvain is eager to share his idea.

Poor, naive Dimitri turns absolutely red before Sylvain has even finished explaining himself, and all he can say is, “Y-you must be joking! …aren’t you?”

“Would I ever joke about something like this?” he replies with a smirk, watching Dimitri’s blush deepen, if such a thing is even possible at this point. “You’re thinking about it, aren’t you, your highness? I’ve seen the way you look at her. If you listen to me and do things the way I tell you to, you’ll have your chance with her.”

“I could never…Sylvain, you can’t just say things like that!”

“And why not? I’m telling the truth, and if you want to sit this one out, then that’s your call, but don’t forget that I was kind enough to offer you a place in my grand plan,” Sylvain teases him. Dimitri still seems hesitant, but already, he can see that he is starting to crack.

~X~

Once he has Dimitri on his side and completely on board with his plan, Sylvain brings him to Byleth’s room at night, where the two of them will wait for her to arrive. He appreciates that Dimitri does not ask too many questions when it comes to how easily he is able to get into the professor’s room, much too nervous thinking about their plans for the night to let his thoughts linger on anything else. Dimitri is almost adorably clueless about everything, but fortunately for both of them, Sylvain knows what he is doing, and will be able to get him through this without much trouble.

He swears that Dimitri stops breathing when the doorknob starts to turn, going stiff as Byleth opens the door, going still as she lets it fall closed behind her, realizing that she has company. Fortunately, she recognizes them immediately, rather than going into survival mode and drawing a sword on them. Sylvain is not sure if either of them could survive an attack from their capable professor.

“What are you two doing here?” she asks, in a surprisingly calm tone of voice. Sylvain puts on his most winning smile as he steps forward, having already promised Dimitri that he would handle the bulk of the talking.

“Professor! It’s so great to see you, I was hoping we would run into you here,” he starts.

“You’re in my room,” she replies, thoroughly unamused.

“Nothing gets passed you! That’s my professor, always on top of things,” he says with a laugh. “The thing is, we both notice just how hard you work. It must be exhausting, being on top of things all the time. So, that’s when I got to thinking, and I thought, hey. Maybe you deserve some time to relax. Maybe it’s time that your two favorite students give back after everything that you have alway given us.”

“Sylvain, what are you getting at? And what, exactly, are you trying to rope Dimitri into?” Byleth is still not buying into his charms, not nearly as easy as the girls he is used to dealing with, but that is part of why he is so interested in her to begin with, and why he definitely can’t let this opportunity pass him by. No matter what, he has to make it out of this having taken what he wants, and given her what he knows that she needs.

“I want to help you relax the best way that I know how. And Dimitri feels the same way, and though he doesn’t know the sort of tricks that I do, you know as well as I just how quick of a study he is.” Giving her that same easy smile, Sylvain continues to close the distance between them, until he is close enough to Byleth to kiss her.

He does, and she is quick to pull out of it, demanding, “What do you think you’re doing?!”

“Like I said, we’re here to help y-”

“You have no idea what you’re doing,” she says, the panic in her voice clear, but even so, he can tell that she is blushing.

“Actually, I know this part pretty well. There’s no need to be so shy, professor. It’s just the three of us in here, after all,” he says in a flirtatious tone, before leaning in again. He half expects her to resist him, or even to slap him before he has the chance, but she does not. In fact, Byleth lets him kiss her, without even trying to resist, giving away just how much the first kiss effected her.

Once he has his professor in his arms, he can actually feel the tension, and can feel just how much she really needs this. He is doing her quite the favor by offering himself up to her like this; even more so, because he has brought Dimitri along with him for the fun. By the time the two of them are done with her, he hopes that she is left feeling happy and relaxed, so much so that, even once she returns to her senses, she is still eager to do more with both of them.

He pushes a hand under her shirt as he kisses her, and she moans into his kiss, going stiff for a moment when she does, but then relaxing again. Oh, she _definitely_ needs this, if nothing is enough to snap her out of her daze. No matter how much she may want to resist this from a moral standpoint, nothing can change just how much she actually wants to be doing this with the two of them, or how much she needs to let her two favorite students take control and show her a good time.

Dimitri watches the two of them, and Sylvain can hear his breathing growing heavier and heavier as he watches the two of them. His temptation is growing, and he wants, more than anything, to join right in with them. His turn will come soon, and Sylvain pulls out of the kiss then, hoping that that is not enough to break the spell. But Byleth seems still just as caught up in it, letting him help her out of her clothes with ragged breathing, pathetic and helpless, giving herself over entirely.

Sylvain helps her onto her back once she is undressed, letting her lay on her bed while he leans over her, resuming their kiss without either of them needing to say a word. His hand finds one of her breasts again, but this time, without her shirt in the way, he is able to do a lot more for her, and make her feel a lot better, pinching one of her nipples between his fingers, teasing at it until she is moaning pathetically, trembling under his touch. And still Dimitri only watches, getting more and more turned on as he does, until Sylvain turns to look at him over his shoulder, breaking the kiss so that he can give him an inviting look.

He does not waste anymore time in getting back to kissing Byleth, though, not bothering to worry about if Dimitri has actually accepted his invitation or not. The only thing that really matters is her pleasure, of course, and if he has to be the only one to do that, then he is certain that he is up to the challenge. Having someone here to help is just an added bonus for Byleth, but he knows that he could tend to her on his own, if he really needed to.

Fortunately for both of them, however, he does not have to put that theory to the test, because Dimitri has joined them in an instant, putting his face between her legs as he kneels over her on the end of the bed. He has no idea what he is doing, and yet he follows his instincts anyway, wanting to give Byleth what she needs some way or another, wanting to show her just how much he wants her by taking good care of her. Tonight, he is going to make sure that she feels better than she ever has before, even if he is completely clueless on how to do that.

The first thing he decides to do is use his mouth. While Sylvain’s mouth is busy with kissing her, his hands busy with her nipples, Dimitri puts his face between her legs right away, knowing nothing about how to eat a woman out, and simply acting on instinct. He pays attention to Byleth’s reactions as he begins to use his tongue on her, trying to figure out what moans are meant for him and what moans are meant for Sylvain, what she really likes and what he needs to repeat, until he has figured things out.

His tongue flicks over her clit and she lets out a sharp cry, just barely muffled by Sylvain’s kiss. Sylvain chuckles, realizing what must have happened, and finds himself feeling strangely proud of Dimitri for figuring that out without needing him to help him along at all. He is not completely hopeless, it seems, and if he keeps things up like this, he might not need Sylvain’s help at all. He might just be able to give Byleth what she needs without needing too much direction.

For now, he is doing just fine, using his mouth to make her whimper, while Sylvain pinches and teases her nipples, pushing her closer and closer to her limit, making her writhe with pleasure. Whatever reservations she may have had before he kissed her are completely forgotten now. She rejected him based on her morals as a professor alone, but she is touch-starved and lonely, having grown up in relative isolation, having never known these kinds of pleasure before. Couple that with the stress of all her hard work as a professor, and there is no way that she could have withstood something like this. Sylvain knew just what she needed, and he knew just how to give it to her.

Now, she is completely helpless, and eager for whatever they may do for her. He is eager as well, ready to show her just what he can do, certain that this is a subject that his professor would give him full marks in. There are plenty of things he could impress her with, but these are matters that he is particularly proud of his skill in. Having another classmate along for the show just helps him prove his point, because he is the one that got Dimitri to loosen up enough to agree to this.

When he can tell that the two of them have her right on the edge, he looks back to Dimitri again and says, “Alright, that’s enough of that for now. Let’s move on to something even more fun!” Dimitri pulls back at his command, and Byleth whines a bit, causing him to look conflicted, not sure which of them he should listen to. It seems that he settles on Sylvain, and the promise of “more fun,” in the end, though.

Sylvain helps so that their positions shift, telling Byleth what he wants her to do while he helps get her ready to take both of them. Since this is something that he plans to do on his own, he has to have some way to keep Dimitri entertained in the meantime, and so, soon enough, the prince is lying naked on his back, with the naked professor kneeling over him, working her hand up and down his cock while he bucks his hips and whines pathetically, his complete lack of experience becoming incredibly apparent in the moment.

But this leaves Byleth completely open for him, and Sylvain came prepared, getting his fingers slick with the lubricant that he brought. While she is bent over in front of him, teasing Dimitri with her hand at first, he is able to spread her cheeks and begin to work one slick finger inside of her. Byleth tenses and freezes at first, squirming with discomfort, a combination of how cold the lube feels on him and not knowing what to do with all of these feelings, but she tries to stay relaxed, as Sylvain has already instructed her to do.

She just keeps doing what she is doing, with Dimitri letting out another pathetic moan as she starts to move her hand up and down again. Sylvain seriously hopes that he will be able to hold out until the end, rather than giving in at the slightest touch from his professor, but for now, he can’t concern himself with babysitting the prince, not when he is working his finger deeper into Byleth’s ass, making her moan with each motion, revealing another side to her. She definitely wants this and definitely likes this, whether she has ever spared it any thought before or not. He will not be the one claiming her ass tonight, but he is at least having plenty of fun making sure that it is ready for Dimitri.

All the while, Dimitri continues to prove that he was not quite ready for this, his voice desperate and pathetic, as he cries out for every stroke of Byleth’s hand. But as Sylvain starts to work a second finger inside of her, she moves on her own, without needing him to instruct her or even put the idea in her head. Byleth simply leans down a little bit further, and wraps her lips around Dimitri’s cock, causing him to let out a strangled and needy cry, surprised and overwhelmed by the sensation of being inside of his professor’s warm, wet mouth.

His very first time with that too; Sylvain would spare more thoughts being proud of the prince if not for the fact that he is much more interesting in fingering Byleth’s ass, and causing her to let out moans that are perfectly muffled by the dick in her mouth. She continues to take Dimitri deeper and deeper, leaning further down over him, and as he loses himself to his pleasure, he jerks and bucks his hips again and again, and yet Byleth manages to take it each time, showing off her surprising lack of limits in this regard.

Despite this being her first time doing anything like this, she almost seems like a natural, which Sylvain never would have guessed from the way she is often staring into space whenever anyone is not directly interacting with her. Maybe all that time, she’s been thinking about how she could blow all these boys’ minds! Not likely, really, but it sure is fun to imagine, and if the professor _did_ turn out to be a secret freak, Sylvain would only be more interested in her, and more eager to spend as much time alone with her as possible.

With two fingers inside of her now, he begins working them in a hooking motion and a scissoring motion, all to feel the way that she opens up for him, so easily and eagerly that it really does seem like she is just begging someone to come fuck her ass already. Dimitri really is a lucky bastard, but Sylvain can’t be too jealous of all of that, considering the fact that he gets Byleth’s virginity- not that the anal virginity doesn’t count, but he knows how a lot of women operate these days. He has met many a woman who seems to believe that as long as it is anywhere but her cunt, she is still as pure as the freshly driven snow. Tonight, Byleth will not be left with any semblance of purity, and he is going to make sure of that.

Three fingers is a bit more effort, and she begins whining around Dimitri’s cock as he eases the third one in, taking his time, not wanting to hurt her or throw everything off curse when they have already come so far. But she is able to take it, when he takes things slowly, and it does not take long for him to have her whining for him all over again. She is nearly ready, which is a good thing, because he does not think Dimitri is going to be able to last much longer, getting sucked off by (Sylvain assumes) the woman of his dreams.

Better that they put a stop to all of this sooner rather than later, so that they can finally get down to what really matters, and take care of what they actually came here to do. Sylvain is growing rather impatient for her himself, so he would prefer not to drag it out much longer. Speaking up, he says, “Let’s switch around again, alright? Don’t worry, you’re staying the middle still, professor.”

The two of them are both so shaky as they move that he is surprised either of them can stand at all. But this time, he is the one on his back, and Byleth will be getting on top of him, rather than sucking him off. She moves so that she can straddle him, looking a bit apprehensive now, but she has still not said anything about wanting to stop, and Sylvain can only assume that she is still just as on board for all of this, just a little more nervous now that it is actually time for the penetration. It will be a lot for her to adjust to, coming from both of them, but they are going to take things slowly, and he has already instructed Dimitri on how best to be gentle with her, to make sure that he does not hurt her in anyway. As for himself, he thinks that he knows well enough how to handle her.

“You can take it at your own pace if you want to,” he says, once she is on top of him, once the tip of his cock is teasing at her entrance. “You’re on top, so that means you can go as slow as you want to. Dimitri will wait until you’re ready, and until then, he’s just going to be watching.”

“I still can’t believe that I’m doing this,” Byleth says in a quiet voice, and Sylvain chuckles. She has been completely swept away in all of this, falling prey to his charms so easily that she still does not realize how she has ended up here. But by the time the two of them are done with her, he knows for sure that she is going to be glad she went along with this, and likely eager to repeat it in the future, if given the chance.

Slowly, she begins to sink down onto his cock. The hesitation is clear in her face, but she knows that she is supposed to relax and take it slow, and he is not doing anything to pressure her or make her do more than she is ready for. Byleth is able to do everything at her own pace, slow and steady, and as Sylvain fills her, he begins to relax beneath her, moaning softly for his professor. Behind her, Dimitri must be losing his mind watching the two of them, but he will have his turn soon enough. Really, with how close he got while she was sucking him off, Sylvain would say that he needs this time to calm down and catch his breath.

As for Byleth, she is not going nearly as slowly as he thought she would, steadily taking him at an impressive pace, a soft moan escaping her lips every now and then, with Sylvain holding her steady, his hands on her waist, helping her ease down onto him, until finally, she has done it. She exhales then, pausing for a moment, and he asks her, “Are you hanging in there alright?”

All she does is nod before she starts to move on top of him, not needing any direction there, simply going with what she wants, and giving Sylvain everything he needs in return. Beneath her, all he can do is relax and moan as she begins riding him in earnest, thrusting up into her once she has her rhythm figured out. When she speaks to him, all she says is, “I want more.”

“You heard her,” he says in a strained voice, calling out to Dimitri, who will finally have his turn. Behind her, Dimitri approaches the two of them, getting up on the bed behind them. Byleth is bent over Sylvain just so, the perfect position for Dimitri to spread her cheeks, prodding against her with his cock. If he takes Sylvain’s lessons to heart, he starts out very slowly, making sure not to rush her as he starts to fit the head of his cock just past her tight hole.

Byleth lets out a sudden and indulgent moan, and Sylvain knows that Dimitri has begun, pushing into her slowly. She slows as well, not bouncing on Sylvain with as much attention anymore, and his thrusts turn slow and lazy as he lets the two of them figure things out and get used to each other. But it is not long before Dimitri is completely buried in her ass, and with Byleth being taken from both sides by two of her beloved students, they both begin to move together, ready to show her what they are capable of together.

Between the two of them, she has no chance to think or worry about anything, letting them handle it all. They thrust in an opposite rhythm, practically bouncing her back and forth between the two of them, with Byleth rocking and crying out, becoming so loud and unrestrained that she sounds nothing like the stoic professor that they have come to know. She is growing suddenly tense, and Sylvain knows just what that means, and knows not to slow down in the slightest, keeping it up, while Dimitri does the same, following his lead, neither of them slowing down until Byleth is trembling with her orgasm, her moan so loud and pathetic that they know this was just what she needed.

Dimitri is right behind her, whining out as he comes, pushed beyond his limits, and so, Sylvain decides that there is no reason for him to hold back as well, giving one weak thrust forward and coming hard. Byleth is filled from both sides as they come, and between them, she goes limp, exhausted and blissed out.

Needless to say, this little tryst has left her much more relaxed, and whether she will admit it or not, she is glad that she agreed to let them help her out like this. Of course, Sylvain and Dimitri are both quick to offer their assistance, whenever she might need it.

**Author's Note:**

> If you're interested in my writing updates, please follow my fanfiction twitter @WattStalf  
> 


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